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From:   Michal Simek <monstr@monstr.eu>
Date:   Mon, 10 Feb 2020 12:48:14 +0100
Message-ID: <CAHTX3dKSq1oTzkoRv3wK3rhkc1r0rOiQhFKmgsYbtG_uvOfAJg@mail.gmail.com>
Subject: Re: [PATCH] rtc: zynqmp: Clear alarm interrupt status before
 interrupt enable
To:     Srinivas Neeli <srinivas.neeli@xilinx.com>
Cc:     Alessandro Zummo <a.zummo@towertech.it>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Srinivas Goud <sgoud@xilinx.com>,
        Shubhrajyoti Datta <shubhraj@xilinx.com>,
        linux-rtc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        linux-arm <linux-arm-kernel@lists.infradead.org>,
        git <git@xilinx.com>
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Hi,

=C4=8Dt 12. 12. 2019 v 14:01 odes=C3=ADlatel Srinivas Neeli
<srinivas.neeli@xilinx.com> napsal:
>
> Fix multiple occurring interrupts for alarm interrupt. RTC module doesn't
> clear the alarm interrupt status bit immediately after the interrupt is
> triggered.This is due to the sticky nature of the alarm interrupt status
> register. The alarm interrupt status register can be cleared only after
> the second counter outruns the set alarm value. To fix multiple spurious
> interrupts, disable alarm interrupt in the handler and clear the status
> bit before enabling the alarm interrupt.
>
> Fixes: 11143c19eb57 ("rtc: add xilinx zynqmp rtc driver")
> Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
> ---
>  drivers/rtc/rtc-zynqmp.c | 29 ++++++++++++++++++++++++-----
>  1 file changed, 24 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
> index 5786866c09e9..d311e3ef1f21 100644
> --- a/drivers/rtc/rtc-zynqmp.c
> +++ b/drivers/rtc/rtc-zynqmp.c
> @@ -38,6 +38,8 @@
>
>  #define RTC_CALIB_DEF          0x198233
>  #define RTC_CALIB_MASK         0x1FFFFF
> +#define RTC_ALRM_MASK          BIT(1)
> +#define RTC_MSEC               1000
>
>  struct xlnx_rtc_dev {
>         struct rtc_device       *rtc;
> @@ -124,11 +126,28 @@ static int xlnx_rtc_alarm_irq_enable(struct device =
*dev, u32 enabled)
>  {
>         struct xlnx_rtc_dev *xrtcdev =3D dev_get_drvdata(dev);
>

here shouldn't be empty line.

> -       if (enabled)
> +       unsigned int status;
> +       ulong timeout;
> +
> +       timeout =3D jiffies + msecs_to_jiffies(RTC_MSEC);
> +
> +       if (enabled) {
> +               while (1) {
> +                       status =3D readl(xrtcdev->reg_base + RTC_INT_STS)=
;
> +                       if (!((status & RTC_ALRM_MASK) =3D=3D RTC_ALRM_MA=
SK))
> +                               break;
> +
> +                       if (time_after_eq(jiffies, timeout)) {
> +                               dev_err(dev, "Time out occur, while clear=
ing alarm status bit\n");
> +                               return -ETIMEDOUT;
> +                       }
> +                       writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_=
STS);
> +               }
> +
>                 writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_EN);
> -       else
> +       } else {
>                 writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_DIS);
> -
> +       }

And here it was good to have empty line.

>         return 0;
>  }
>
> @@ -183,8 +202,8 @@ static irqreturn_t xlnx_rtc_interrupt(int irq, void *=
id)
>         if (!(status & (RTC_INT_SEC | RTC_INT_ALRM)))
>                 return IRQ_NONE;
>
> -       /* Clear RTC_INT_ALRM interrupt only */
> -       writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_STS);
> +       /* Disable RTC_INT_ALRM interrupt only */
> +       writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_DIS);
>
>         if (status & RTC_INT_ALRM)
>                 rtc_update_irq(xrtcdev->rtc, 1, RTC_IRQF | RTC_AF);
> --
> 2.7.4

Other then these two above things look good.

Alexandre: Any issue with this patch?

Thanks,
Michal

--=20
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Xilinx Microblaze
Maintainer of Linux kernel - Xilinx Zynq ARM and ZynqMP ARM64 SoCs
U-Boot custodian - Xilinx Microblaze/Zynq/ZynqMP/Versal SoCs